Low back pain (LBP) is the most frequently reported musculoskeletal problem and third most frequently reported symptom of any kind in people over the age of 75. In fact, 17.3% of all visits to physicians for LBP involve individuals over 65. In older adults, LBP has been associated with a host of negative consequences, including decreased physical function, increased fall risk, increased mood disturbance and increased healthcare utilization. Surprisingly, little research has focused on LBP in people over 65. But, recent evidence demonstrates that LBP is associated with increased intramuscular fat infiltration in the abdominal and paraspinal muscles and that this altered muscle composition increases the risk of mobility-related functional decline in older adults. While trunk muscle training (TMT) has been used in younger LBP groups, it is unproven in elders and, alone, may not be sufficient to substantially improve function and symptoms, given the compromised state of aged muscle. TMT augmented with neuromuscular electrical stimulation (NMES), known to improve strength and function beyond the capacity of volitional exercise alone, may provide greater improvements. Treatment of chronic LBP in older adults using an exercise intervention has been hypothesized as a way to prevent functional decline and frailty progression;however, this hypothesis has yet to be experimentally confirmed. In this exploratory study, we will test the hypothesis that TMT plus NMES will result in reduced disability and pain severity compared to usual care in elders with chronic LBP. Using a randomized controlled experimental design, 62 community dwelling older adults age 65-85 with chronic LBP who never had spinal surgery, and have no prominent pain in sites other than the back, will receive either (1) TMT augmented with NMES or (2) a passive, control intervention twice a week for 12 weeks. Prior to randomization, immediately after the last treatment session and 3 months later, the following parameters will be assessed by a masked evaluator: self-reported disability as measured by the Oswestry Disability Questionnaire, pain severity as measured by the Pain Thermometer, physical function as measured by performance-based measures, and psychosocial function (mood, self-efficacy, self-rated health, and pain-related fear). Magnetic resonance imaging will be done at baseline and immediately after last treatment session to evaluate muscle composition and its underlying role in perpetuating the pain-disability cycle. If this exploratory study suggests that TMT+NMES is effective, future studies with longer follow-up periods will be designed to investigate its efficacy for preventing functional decline and determine the impact on healthcare costs. Practice guideline changes will not occur without compelling evidence that exercise interventions for elders with chronic LBP result in reduced disability and are cost-effective. PUBLIC HEALTH RELEVANCE: Given the prevalence of chronic low back pain (LBP) in community dwelling older adults and the associated negative functional consequences, this research will have a broad impact on public health as there has been limited research aimed at reducing pain and disability in the geriatric population with LBP. The potential benefits of this research include: (a) improving quality of life for community-dwelling older adults with chronic LBP by improving pain management, as well as physical and psychosocial function;(b) developing a non-pharmacologic treatment for elders with chronic LBP, and thus protecting future individuals from exposure to potentially toxic medications;and (c) future development of studies focused on decreasing health care utilization costs.